Author:

Thomas Russell(University of Massachusetts)

We have taken a new approach to develop mesoporous lead iodide scaffolds,
using the nucleation and growth of lead iodide crystallites in a wet film. A
simple time-dependent growth control enabled the manipulation of the
mesoporous lead iodide layer quality in a continuous manner. The morphology
of lead iodide is shown to influence the subsequent crystallization of
methyamoniumleadiodide film by using angle-dependent grazing incidence x-ray
scattering. The morphology of lead iodide film can be fine-tuned, and thus
the methyamoniumleadiodide film quality can be effectively controlled,
leading to an optimization of the perovskite active layer. Using this
strategy, perovskite solar cells with inverted PHJ structure showed a \textit{PCE} of
15.7 per cent with little hysteresis. Interface engineering is critical for
achieving efficient solar cells, yet a comprehensive understanding of the
interface between metal electrode and electron transport layer (ETL) is
lacking. A significant power conversion efficiency (PCE) improvement of
fullerene/perovskite planar heterojunction solar cells was achieved by
inserting a fulleropyrrolidine interlayer between the silver electrode and
electron transport layer. The interlayer was found to enhance recombination
resistance, increases electron extraction rate and prolongs free carrier
lifetime. We also uncovered a facile solution-based fabrication of high
performance tandem perovskite/polymer solar cells where the front sub-cell
consists of perovskite and the back sub-cell is a polymer-based layer. A
record maximum PCE of 15.96 per cent was achieved, demonstrating the synergy
between the perovskite and semiconducting polymers. This design balances the
absorption of the perovskite and the polymer, eliminates the adverse impact
of thermal annealing during perovskite fabrication, and affords devices with
no hysteresis.

*This work was performed in collaboration with Y. Liu, Z. Page, D. Venkataraman and T. Emrick (UMASS), F. Liu (LBNL) and Q. Hu and R. Zhu (Peking University) and was supported by the Office of Naval Research under contract N00014-15-1-2244xx.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2016.MAR.V4.1